The National, stable isotopes resource at Los Alamos is dedicated to the development of the stable isotopes of carbon (12C, 13C), oxygen (16O, 17O, 18O), and nitrogen (14N, 15N) in the biosciences, especially within the NIH community, and has the following functions: 1) The production of separated 13C, 15N, and 18O at the multi-kilogram per year level by the low temperature distillation of carbon monoxide and nitric oxide. 2) The synthesis of labeled compounds for properly accredited investigators when commercial or other sources are not readily available at an acceptable cost and when the synthetic procedures exist or can be practically developed at LASL. 3) The development of an active program of research collaboration with investigators in the biosciences community providing, as necessary, isotope labeled compounds, nmr, and isotope-ratio mass spectrometric analysis, and data interpretation. 4) The provision of advice and assistance to properly accredited investigators regarding experimental plans and operations which involve the use of stable isotopes. 5) The hosting of visiting scientists for training in the use of stable isotopes and the encouragement of exchanges of talks, short courses, and sabbaticals. 6) The collaboration with other resources in isotope synthesis and mass spectrometric and nmr analyses to accelerate development of isotope methodology. 7) The performance of core research designed to keep the resource at a 'state-of-the-art' level.